深冷激光喷丸强化2024-T351铝合金的表面力学性能

为了研究深冷激光喷丸强化（Cryogenic Laser Peening，CLP）对2024-T351铝合金表面力学性能的影响，采用Nd:YAG纳秒脉冲激光分别在常温（25℃）和深冷温度（-100℃）条件下对2024-T351铝合金材料进行激光喷丸处理，随后对试样的显微硬度、残余应力和微观组织等表面性能进行了测试分析，最后基于微观组织演变探讨了CLP对2024-T351铝合金的强化机理。结果表明，由于超低温对位错滑移及湮灭的抑制作用，CLP处理试样的位错密度提高，在动态再结晶后材料表面晶粒尺寸减小，其表层显微硬度与残余压应力值较常温LP处理试样分别提高了约20.3%与21.6%，因而改善了2024-T351铝合金的表面力学性能。

Surface mechanical properties of 2024-T351 aluminum alloy strengthened by cryogenic laser peening

In order to investigate the effects of cryogenic laser peening(CLP) on the surface mechanical properties of 2024-T351 aluminum alloy, the Nd:YAG nanosecond pulsed laser was used to carry out the laser peening on 2024-T351 aluminum alloy at room temperature(25℃) and cryogenic temperature(-100℃), respectively. The micro-hardness, residual stress and microstructure of the samples were tested and analyzed, and the strengthening mechanism of CLP was discussed by the laser induced microstructure at room temperature and cryogenic temperature. The results show that, the dislocation density of CLP-treated samples is higher and the grain size on the surface is smaller than that of LPed after dynamic recrystallization due to the effect of cryogenic temperature on the sliding and annihilation of the dislocation. The surface micro-hardness and residual compressive stress of CLP-treated samples are respectively increased by about 20.3% and 21.6%, compared with LP samples, and the surface mechanical properties of 2024-T351 aluminum alloy are improved.